Sulfhydryl groups in relation to the metabolism and motility of human spermatozoa.

1. The motility and metabolism of human spermatozoa are inhibited by substances which have an affinity for sulfhydryl groups. 2. These inhibitions can be prevented, and in part, reversed, by the addition to the cell + inhibitor system of sulfhydryl compounds such as cysteine or glutathione. 3. Cysteine and glutathione, under aerobic conditions or in a system in which these substances can be oxidized, show widely different effects on the motility of the spermatozoa. Cysteine destroys the motility of the spermatozoa, whereas glutathione has no effect upon it. 4. Possible mechanisms of these effects are discussed.